Exploiting Timing Error Resilience in Processor Architecture

Abstract

Escalating variations in modern CMOS designs have become a threat to Moore’s law. In light of the increasing costs of standard worst-case design practices, timing speculation has become a popular approach for dealing with static and dynamic non-determinism and increasing yield. Timing speculative architectures allow conservative guardbands to be relaxed, increasing efficiency at the expense of occasional errors, which are corrected or tolerated by an error resilience mechanism. Previous work has proposed circuit- or design-level optimizations that manipulate the error rate behavior of a design to increase the efficiency of timing speculation. In this article, we investigate whether architectural optimizations can also manipulate error rate behavior to significantly increase the effectiveness of timing speculation. To this end, we demonstrate how error rate behavior indeed depends on processor architecture and that architectural optimizations can be used to manipulate the error rate behavior of a processor. Using timing speculation-aware architectural optimizations, we demonstrate enhanced overscaling and up to 29% additional energy savings for processors that employ Razor-based timing speculation.